Preheat the grill to 350°F preparing for indirect grilling.
In a large bowl combine the flour, sugar, baking powder and cinnamon. Make a well in the flour mixture and add the egg, vanilla, milk, lemon juice and butter. Stir until they are just combined, and then using a hand mixer, mix on medium-high for 60 seconds.
Pour the batter evenly between two prepared baking pans of the same size and bake indirectly on the grill for 30 minutes, or until a toothpick comes out completely clean.
Allow it to cool completely before removing the cakes from the pans.
In double boiler or a heatproof bowl, whisk egg yolks, sugar, lemon zest and lemon juice over saucepan of simmering water. Cook the lemon mixture, stirring, until it is thick enough to coat back of your spoon, about 8 minutes.
Remove the lemon mixture from the heat and stir in the butter, 1 piece at a time, until smooth.
Put the lemon curd into an airtight container, cover the top with plastic wrap before putting on the lid. Then refrigerate for 2 hours or until it sets.
While the lemon curd is setting, place a mixing bowl into the freezer (glass, pyrex or metal) to chill. When sufficiently chilled, whip the cream, icing sugar and vanilla together until stiff peaks form. Fold in the mascarpone cheese. If you cannot get mascarpone cheese you can combine 4 oz. of cream cheese at room temperature with ¼ cup of whipping cream and the 2½ tbsp. of sour cream. Mix until smooth then fold into the whipped cream instead of mascarpone. Refrigerate until needed.
When you are ready to assemble the cake, cut off the rounded top of one or both cakes. Spread the lemon curd evenly over the first layer, then gently lay the second layer on top. Ice with the mascarpone icing and garnish with strawberry slices and lemon zest. Chill until ready to serve.